I lost money in NovatechFx Ponzi scheme, can I file Form 4684

You can claim a casualty loss deduction using Form 4684 for Ponzi scheme losses; however, the issues of when the qualifying theft occurred and the relevant dollar amounts can be quite complex. 

The TurboTax in-program guidance at a Learn More link in the Casualty Loss section states:

"We're sorry to hear about this loss. Unfortunately, this type of loss can be particularly complicated for tax purposes, and in many situations the tax treatment depends on factual determinations best handled by an attorney. TurboTax does not support tax losses from investment fraud. We recommend consulting a tax professional if you've experienced this situation."

The IRS Instructions for Form 4684 explain how to report a theft loss deduction for a Ponzi-type investment scheme. 

The IRS provides two items of guidance to help taxpayers who are victims of losses from Ponzi-type investment schemes:

• Revenue Ruling 2009-9 PDF provides guidance on determining the amount and timing of losses from these schemes, which is difficult and dependent on the prospect of recovering the lost money (which may not become known for several years).
   
• Revenue Procedure 2009-20 PDF simplifies compliance for taxpayers by providing a safe-harbor means of determining the year in which the loss is deemed to occur and a simplified means of computing the amount of the loss.

See this IRS webpage for more information for taxpayers affected by Ponzi scheme losses.